Dietary maladvice as a cause of hypothyroidism and short stature

Iodine Status and Growth In 0-2-Year-Old Infants With Cow's Milk Protein Allergy

OBJECTIVES

The aim of the present article was to investigate iodine status and growth in cow's milk protein allergic infants and to identify potential predictors of iodine status and growth.

METHODS

Fifty-seven infants under 2 years of age were included in an observational cross-sectional study. Two spot urine samples were collected and analyzed for iodine, together with a 3-day food record and a food frequency questionnaire. Urine iodine concentrations were compared with the WHO cut-off values for iodine deficiency. Measurements of weight, length, and head circumference at birth and study inclusion were converted to standard deviation scores. Subgroup analyses were performed on different feeding patterns, according to weaning status.

RESULTS

Median age was 9 months. Median urinary iodine concentration was 159 ug/L. One third of the children had urine iodine concentrations indicating iodine deficiency. Infants who were mainly breastfed were at highest risk and 58% were classified as deficient. Dietary factors positively associated with iodine excretion were intake of enriched baby cereals and meeting the dietary requirement for iodine. Stunting was present in 5%. Underweight and wasting was frequent at 11% and this was associated with food refusal and poor appetite, but not with iodine status. Growth failure was detected among boys.

CONCLUSIONS

The present study suggests that cow's milk protein allergy children have high prevalence of iodine deficiency and poor growth, however the 2 conditions were not associated. The subgroup of mainly breastfed infants was at higher risk of iodine deficiency compared to weaned infants. Subjects with feeding problems had increased risk of malnutrition.

Iodine Deficiency and Hypothyroidism From Voluntary Diet Restrictions in the US: Case Reports

Iodine deficiency is rare in the United States today, and this is largely due to the effectiveness of iodization in the general food supply. Recent trends among specific populations of children in the United States include adopting food restrictions, such casein-free and gluten-free diets. Although the effect of these types of diets on overall nutrition status and certain micronutrients has been studied in children with autism spectrum disorder, the effect of these limitations on iodine levels in children has not been assessed. We present here 2 cases of iodine deficiency resulting from severe food restriction and associated primary hypothyroidism. In 1 case a classic presentation with a goiter was seen. These children were able to discontinue thyroid hormone treatment once iodine levels were normalized. There were no adverse events or unanticipated outcomes. The occurrence of these cases of iodine deficiency in the United States points to the need for thyroid function testing in children with severe food restrictions, especially those who have limited exposure to dairy, baked goods, and table salt.

Dietary restriction causing iodine-deficient goitre

Iodine-deficient goitre was common in some parts of the UK prior to the introduction of salt iodisation. Many contemporary salt preparations do not contain much iodine, and there are renewed concerns about the iodine status of the population. We present a boy with severe allergy who developed goitre and significant thyroid dysfunction in association with an iodine-deficient 'food-restricted' diet. The case highlights the importance of a comprehensive nutritional assessment in all children on multiple food restrictions.

Hashimoto's thyroiditis: TGAb, TPOAb, TRAb and recovery from hypothyroidism

Hashimoto described four patients with goiter. The histology of the goiter was characterized by diffuse lymphocytic infiltration, fibrosis and epithelial cell destruction. Thyroglobulin antibody (TGAb) and thyroid peroxidase antibody (TPOAb) have been used to diagnose Hashimoto's thyroiditis. Patients with positive TGAb and/or TPOAb have been assumed to have Hashimoto's thyroiditis. Approximately 10% of those with positive TGAb and/or TPOAb have hypothyroidism. There are two types of autoimmune thyroiditis: goitrous Hashimoto's thyroiditis and atrophic thyroiditis. The latter patients have blocking antibody (thyroid-stimulating hormone [TSH]-stimulation blocking antibody [TSBAb]). TSBAb is a TSH-receptor antibody (TRAb). TSBAb causes thyroid atrophy and hypothyroidism. TGAb and/or TPOAb do not necessarily cause hypothyroidism. Hypothyroid patients with Hashimoto's thyroiditis usually receive life-long l-thyroxine therapy. However, spontaneous recovery from hypothyroidism has been reported. Patients who had Hashimoto's hypothyroidism and then Graves' hyperthyroidism (and vice versa), have also been reported. Hashimoto's hypothyroidism and Graves' hyperthyroidism could be the opposite spectrums of one disease.

Endocrine-disrupting chemicals: an Endocrine Society scientific statement

There is growing interest in the possible health threat posed by endocrine-disrupting chemicals (EDCs), which are substances in our environment, food, and consumer products that interfere with hormone biosynthesis, metabolism, or action resulting in a deviation from normal homeostatic control or reproduction. In this first Scientific Statement of The Endocrine Society, we present the evidence that endocrine disruptors have effects on male and female reproduction, breast development and cancer, prostate cancer, neuroendocrinology, thyroid, metabolism and obesity, and cardiovascular endocrinology. Results from animal models, human clinical observations, and epidemiological studies converge to implicate EDCs as a significant concern to public health. The mechanisms of EDCs involve divergent pathways including (but not limited to) estrogenic, antiandrogenic, thyroid, peroxisome proliferator-activated receptor gamma, retinoid, and actions through other nuclear receptors; steroidogenic enzymes; neurotransmitter receptors and systems; and many other pathways that are highly conserved in wildlife and humans, and which can be modeled in laboratory in vitro and in vivo models. Furthermore, EDCs represent a broad class of molecules such as organochlorinated pesticides and industrial chemicals, plastics and plasticizers, fuels, and many other chemicals that are present in the environment or are in widespread use. We make a number of recommendations to increase understanding of effects of EDCs, including enhancing increased basic and clinical research, invoking the precautionary principle, and advocating involvement of individual and scientific society stakeholders in communicating and implementing changes in public policy and awareness.

Goiter and multiple food allergies

Severe iodine deficiency results in impaired thyroid hormone synthesis and thyroid enlargement. In the United States, adequate iodine intake is a concern for women of childbearing age and pregnant women. Beyond this high risk group iodine deficiency is not considered to be a significant problem. This case report describes a 12-year-old male with severe iodine deficiency disorder (IDD) resulting from restricted dietary intake due to multiple food allergies. We describe iodine replacement for this patient and continued monitoring for iodine sufficiency. Children with multiple food allergies, in particular those with restrictions to iodized salt and seafood, should be considered high risk for severe iodine deficiency.

Current and Potential Rodent Screens and Tests for Thyroid Toxicants

This article reviews current rodent screens and tests to detect thyroid toxicants. Many points of disruption for thyroid toxicants are outlined and include: (a) changes in serum hormone level; (b) thyroperoxidase inhibitors; (c) the perchlorate discharge test; (d) inhibitors of iodide uptake; (e) effects on iodothyronine deiodinases; (f) effects on thyroid hormone action; and (g) role of binding proteins (e.g., rodent transthyretin). The major thyroid endpoints currently utilized in existing in vivo assay protocols of the Organization for Economic Cooperation and Development (OECD), Japanese researchers, and U.S. Environmental Protection Agency (EPA) include thyroid gland weight, histopathology, circulating thyroid hormone measurements, and circulating thyroid-stimulating hormone (TSH). These endpoints can be added into the existing in vivo assays for reproduction, development, and neurodevelopment that are outlined in this chapter. Strategic endpoints for possible addition to existing protocols to detect effects on developmental and adult thyroid endpoints are discussed. Many of these endpoints for detecting thyroid system disruption require development and additional research before they can be considered in existing assays. Examples of these endpoints under development include computer-assisted morphometry of the brain and evaluation of treatment-related changes in gene expression, thyrotropin-releasing hormone (TRH) and TSH challenge tests, and tests to evaluate thyroid hormone (TH)-dependent developmental events, especially in the rodent brain (e.g., measures of cerebellar and cortical proliferation, differentiation, migration, apoptosis, planimetric measures and gene expression, and oligodendrocyte differentiation). Finally, TH-responsive genes and proteins as well as enzyme activities are being explored. Existing in vitro tests are also reviewed, for example, thyroid hormone (TH) metabolism, receptor binding, and receptor activation assays, and their restrictions are described. The in vivo assays are currently the most appropriate for understanding the potential effects of a thyroid toxicant on the thyroid system. The benefits and potential limitations of the current in vivo assays are listed, and a discussion of the rodent thyroid system in the context of human health is touched upon. Finally, the importance of understanding the relationship between timing of exposure, duration of dose, and time of acquisition of the endpoints in interpreting the results of the in vivo assays is emphasized.

Genistein and other soya isoflavones are potent ligands for transthyretin in serum and cerebrospinal fluid

Consumption of soya-based nutrients is increasing in modern society because of their potentially protective effects against chronic diseases. Soya products are also heavily advertised as alternative drugs for relief from symptoms of the menopause and for hormone replacement therapy. However, because of their oestrogenic activity, negative effects of isoflavones have been postulated. Therefore, we analysed influences of soya isoflavones, major soya constituents with endocrine activity, on thyroxine (T4) binding to its distribution proteins. Serum binding of (125)I-labelled L-T4 was analysed in the absence or presence of increasing concentrations of soya isoflavones using non-denaturing PAGE for analysis. Complete displacement of [(125)I]T4 binding to transthyretin (TTR) was observed in human serum incubated with genistein at concentrations >10 microM; interference started at >0.1 microM. Glycitein showed decreased and daidzein the lowest displacement potency. [(125)I]T4 was displaced to albumin in rat and to T4-binding globulin in human serum. Soya isoflavones also obstruct [(125)I]T4 binding to TTR in human cerebrospinal fluid (CSF). The inhibitory effect was confirmed in direct binding assays using purified TTR with 50% inhibitory concentration values of 0.07 microM for genistein, 0.2 microM for glycitein and 1.8 microM for daidzein. The present study underlined a potent competition of soya isoflavones for T4 binding to TTR in serum and CSF. Isoflavones might alter free thyroid hormone concentrations resulting in altered tissue availability and metabolism. As a consequence of this interference, one could expect a disturbance in the feedback regulation of hormonal networks, including the pituitary-thyroid-periphery axis during development and in adult organisms.

Inactivation of thyroid peroxidase by soy isoflavones, in vitro and in vivo

Soy-containing foods and dietary supplements are widely consumed for putative health benefits (e.g. cancer chemoprevention, beneficial effects on serum lipids associated with cardiovascular health, reduction of osteoporosis, relief of menopausal symptoms). However, studies of soy isoflavones in experimental animals suggest possible adverse effects as well (e.g. enhancement of reproductive organ cancer, modulation of endocrine function, anti-thyroid effects). This paper reviews the evidence in humans and animals for anti-thyroid effects of soy and its principal isoflavones, genistein and daidzein.

Goitrogenic and estrogenic activity of soy isoflavones

Soy is known to produce estrogenic isoflavones. Here, we briefly review the evidence for binding of isoflavones to the estrogen receptor, in vivo estrogenicity and developmental toxicity, and estrogen developmental carcinogenesis in rats. Genistein, the major soy isoflavone, also has a frank estrogenic effect in women. We then focus on evidence from animal and human studies suggesting a link between soy consumption and goiter, an activity independent of estrogenicity. Iodine deficiency greatly increases soy antithyroid effects, whereas iodine supplementation is protective. Thus, soy effects on the thyroid involve the critical relationship between iodine status and thyroid function. In rats consuming genistein-fortified diets, genistein was measured in the thyroid at levels that produced dose-dependent and significant inactivation of rat and human thyroid peroxidase (TPO) in vitro. Furthermore, rat TPO activity was dose-dependently reduced by up to 80%. Although these effects are clear and reproducible, other measures of thyroid function in vivo (serum levels of triiodothyronine, thyroxine, and thyroid-stimulating hormone; thyroid weight; and thyroid histopathology) were all normal. Additional factors appear necessary for soy to cause overt thyroid toxicity. These clearly include iodine deficiency but may also include additional soy components, other defects of hormone synthesis, or additional goitrogenic dietary factors. Although safety testing of natural products, including soy products, is not required, the possibility that widely consumed soy products may cause harm in the human population via either or both estrogenic and goitrogenic activities is of concern. Rigorous, high-quality experimental and human research into soy toxicity is the best way to address these concerns. Similar studies in wildlife populations are also appropriate.

Reported adverse food reactions overestimate true food allergy in the community

OBJECTIVE

To determine the extent to which perceived adverse food reactions were associated with IgE mediated food allergy, as defined by skin prick testing (SPT).

DESIGN

A cohort epidemiological study. Participants underwent SPT to five common food allergens (cow's milk, peanut mix, egg white, shrimp and whole grain wheat mix) and were asked whether they had ever suffered any food 'illness/trouble', and if so to list such food(s). A positive SPT was defined as wheal diameter of > or =3 mm. Cohen's kappa (kappa) was used to assess the agreement between SPT and self-reported reactions to food(s) which contained the allergen of interest.

SETTING

Randomly selected adults who took part in the follow-up of the European Community Respiratory Health Survey (ECRHS) in 1998.

SUBJECTS

The subjects were 457 adults aged 26-50 y.

RESULTS

Fifty-eight (13%) adults were sensitised to at least one food allergen whilst 99 adults (22%) reported illness to food(s) nearly always. However, only seven subjects who reported illness to a food also had a positive SPT to the same food. The prevalence of adverse food reactions associated with IgE mediated allergy in the adult general population would be less than 1.5% (7/457). The agreement between SPT and self-reported illness to food(s) was poor for cow's milk (kappa=0) and wheat (kappa=0), slight for shrimp (kappa=0.16) and egg white (kappa=0.09) and fair for peanut mix (kappa=0.37).

CONCLUSIONS

There was little agreement between self-reported perceived illness to food(s) known to contain the food allergen of interest, and positive SPT, suggesting that most reactions are not due to IgE mediated food allergy.

Nutrition basics in food allergy

Strict elimination of foods because of food allergies can interfere with good nutrition. It is essential that the diagnosis of a food allergy be proven thoroughly to avoid unnecessary food restrictions. Comprehensive education should show where allergenic foods are found, how to find appropriate substitutes for the eliminated foods and corresponding nutrients, and how to avoid accidental ingestion of allergenic foods. A nutrition assessment is an essential part of the clinical follow-up. Identifying nutrition-related problems early can correct difficult situations and prevent long-term health consequences.

Dietary genistein inactivates rat thyroid peroxidase in vivo without an apparent hypothyroid effect

Biological effects of genistein are currently under investigation by the National Toxicology Program because of widespread and increasing soy consumption by humans and evidence for modulation of endocrine function. Rats were exposed to genistein aglycone in soy-free feed fortified at 0, 5, 100, and 500 ppm starting in utero through 20 weeks. Thyroid glands and serum were analyzed for total genistein (aglycone + conjugates) using HPLC with electrospray mass spectrometric detection. Microsomal thyroid peroxidase (TPO) activity was measured spectrophotometrically. The total genistein content in rat serum was as high as 8 microM, and significant dose-dependent increases of genistein in thyroid tissue up to 1 pmol/mg were found in male and female rats. The activity of TPO in male and female rats was found to be reduced by up to 80% in a dose-dependent manner. Male and female rats consuming a standard soy-based rodent diet (NIH 31) had TPO activity approximately 50% lower than rats consuming a soy-free diet and this loss was commensurate with measured serum levels of isoflavones. Suicide inactivation of rat, porcine, and human TPO was observed in vitro at concentrations of genistein aglycone comparable to those measured in rat thyroids. Thyroid hormone levels (T3, T4, TSH) in serum, thyroid weights, and histopathology showed no differences between treated and untreated groups. These findings suggest that, even though substantial amounts of TPO activity are lost concomitant to soy isoflavone consumption by normal rats, the remaining enzymatic activity is sufficient to maintain thyroid homeostasis in the absence of additional perturbations.

Public perception of food allergy

Although studies that use the double-blind placebo-controled food challenge (DBPCFC) suggest that the prevalence of food allergy is about 2%, public belief in food allergy appears to be considerably higher. The study was undertaken to determine the magnitude and features of the American public's belief in food allergy by surveying a large, demographically balanced population. A simple question about food allergy was incorporated into a broad, self-reported, mailed consumer questionnaire. Demographically representative American households (5000) were surveyed by means of quota sample in 1989, 1992, and 1993. The response rate was 79, 75, and 74%, respectively. Of responding households, 16.2, 16.6, and 13.9%, respectively, of responding households reported an average of 1.17 household members with food allergy. Individuals reported to be allergic to foods were more likely to be female, particularly adult women. Male individuals with reported food allergy tended to be young, whereas no such skew was noted among female subjects. Geographic differences were observed in reported food allergy, with the highest rate in the Pacific region. Milk and chocolate were the individual foods most frequently implicated in food allergy. Trends were consistent over the time period studied. Perceived food allergy is widespread and persistent. The characteristics and demographic patterns of this belief are not reflective of known food allergy epidemiology derived from studies in which the DBPCFC is used.

Public perception of food allergy

BACKGROUND

Although studies that use the double-blind placebo-controlled food challenge suggest that the prevalence of food allergy is about 2%, public belief in food allergy appears to be considerably higher.

OBJECTIVE

The study was undertaken to determine the magnitude and features of the American public's belief in food allergy by surveying a large, demographically balanced population.

METHODS

A simple question about food allergy was incorporated into a broad, self-reported, mailed consumer questionnaire. Five thousand demographically representative American households were surveyed by means of quota sample in 1989, 1992, and 1993.

RESULTS

The response rates were 79%, 75%, and 74%, respectively. Of responding households, 16.2%, 16.6%, and 13.9%, respectively, reported an average of 1.17 household members with food allergy. Individuals reported to be allergic to foods were more likely to be female, particularly adult women. Male individuals with reported food allergy tended to be young, whereas no such skew was noted among female subjects. Geographic differences were observed in reported food allergy, with the highest rate in the Pacific region. Milk and chocolate were the individual foods most frequently implicated in food allergy. Trends were consistent over the period studied.

CONCLUSIONS

Perceived food allergy is widespread and persistent. The characteristics and demographic patterns of this belief are not reflective of known food allergy epidemiology derived from studies in which the double-blind placebo-controlled food challenge is used.

Healthy eating for infants--mothers' attitudes

Mothers' perceptions of desirable nutritional practices in infant feeding were examined using a questionnaire consisting of open and closed questions. A total of 1004 mother-infant pairs were recruited from a mixture of urban and rural areas in England. The sample represented a cross-section of socioeconomic groups and educational backgrounds. Mothers' attitudes to healthy eating for infants revealed some misconceptions; 83% felt that a high fibre intake was important or very important and 87% that a low fat intake was important or very important, while 20% considered that plenty of calories was not important. Other health guidelines were appropriately applied and most mothers considered a wide variety of foods, plenty to drink and a low sugar and salt intake to be important. These beliefs were representative of the sample population, irrespective of the socioeconomic group, location, age and education of the mother.

[Digestive manifestations of food hypersensitivity in adults]

Food allergy, synonymous with food hypersensitivity (FHS), is defined as an immunologically-mediated adverse reaction to food. Initiation of FHS could result from a break in the immune mucosal barrier with abrogation of oral tolerance. Food hypersensitivity is mostly due to immediate-type reaction involving IgE-dependent mastocytes activation. Changes in intestinal function and structure have been mainly studies in an animal model of rat sensitized to egg albumin. Intraluminal antigen challenge resulted in abnormalities of gut absorption, secretion and motility in sensitized rats. In man, experimental data are scarce. Gastrointestinal manifestations of immediate FHS are varying and unspecific. A role for FHS in irritable bowel syndrome is debated. Participation of delayed-type FHS to digestive diseases is still questionable, but eosinophilic gastroenteritis might be an example. In clinical practice, diagnosis of FHS demands rigorous criteria. Double blind placebo-controlled food challenge has eventually proved to be the "gold standard" test for FHS diagnosis.